Hmm. It depends. On a lot of things.
How much time is involved here? One hour a day all year? Fifteen minutes twice a week for a couple months?
How unique is the information?
What is the cause of the dislike? Does the child think it’s too hard? Too easy? Too boring? Does he disagree with it philosophically?
What lesson does the child need to learn most right now? The info in the book? General stick-to-itiveness? That life is too short for bad writing?
In 5 years, will one of you regret not finishing it? Or will one of you still be bemoaning lost time?
It’s complicated. “It depends.” What does your dh and your Father say?